ASE L2 Domain 2: Electronic Engine Controls Diagnosis Welcome to your ASE L2 Domain 2: Electronic Engine Controls Diagnosis 1. ASE L2: Electronic Engine Controls Diagnosis During the diagnosis of the electronic control system of a diesel engine, a technician finds a DTC for low voltage to the intake air heater circuit. What is the most likely cause? A. Blown fuse in the air heater circuit B. Malfunctioning air intake temperature sensor C. Open circuit in the heater element D. Faulty air heater relay None 2. ASE L2: Electronic Engine Controls Diagnosis What could cause a diesel engine's ECM to register a false over-speed condition, causing an unwarranted engine shutdown? A. Damaged crankshaft position sensor B. Restricted fuel return line C. Faulty turbocharger wastegate actuator D. Defective vehicle speed sensor None 3. ASE L2: Electronic Engine Controls Diagnosis If a diesel engine's ECM enters a limp mode and sets a code for "Turbocharger Boost Control Position Sensor Circuit Range/Performance," which component should be inspected first? A. Turbocharger compressor inlet B. Boost control solenoid C. Vane position sensor D. Intercooler assembly None 4. ASE L2: Electronic Engine Controls Diagnosis When diagnosing an electronically controlled diesel engine that has a delayed start condition, a technician notes that the ICP (Injection Control Pressure) is lower than specified during cranking. What is the LEAST likely cause? A. ICP sensor malfunction B. Weak high-pressure oil pump C. Leaking injector o-rings D. Malfunctioning glow plugs None 5. ASE L2: Electronic Engine Controls Diagnosis An electronically controlled diesel engine is not responding to throttle input. A DTC indicates a fault in the throttle position sensor circuit. What should be checked FIRST? A. Throttle position sensor (TPS) supply voltage B. ECM power and ground circuits C. Accelerator pedal assembly D. Wiring harness for the TPS None 6. ASE L2: Electronic Engine Controls Diagnosis A technician observes erratic behavior of the fuel gauge and the temperature gauge on a diesel engine vehicle. No relevant DTCs are stored. What is the most likely cause? A. Instrument cluster failure B. ECM software in need of an update C. Loose connection at the body control module (BCM) D. Failing alternator causing electrical noise None 7. ASE L2: Electronic Engine Controls Diagnosis In a common rail diesel injection system, the high-pressure pump is not achieving desired pressure. A DTC for low rail pressure is present. What is the MOST likely cause? A. Faulty fuel rail pressure sensor B. Air in the fuel system C. Clogged fuel filter D. Weak battery causing low engine cranking speed None 8. ASE L2: Electronic Engine Controls Diagnosis A technician is diagnosing an intermittent stalling issue on a diesel engine. The engine stalls when hot but restarts after cooling down. The stalling is accompanied by loss of RPM signal. What is the most likely culprit? A. Faulty crankshaft position sensor B. Defective ECM C. Overheating fuel pump D. Malfunctioning coolant temperature sensor None 9. ASE L2: Electronic Engine Controls Diagnosis The Check Engine Light of a diesel engine vehicle comes on, and the vehicle enters limp mode. The DTC indicates "Low Voltage at Fuel Quantity Actuator." What is the FIRST step in troubleshooting this issue? A. Replace the fuel quantity actuator B. Test the actuator control circuit for shorts to ground C. Measure the resistance of the fuel quantity actuator D. Check the voltage supply to the fuel quantity actuator None 10. ASE L2: Electronic Engine Controls Diagnosis What diagnostic test should be performed FIRST when a diesel engine has low power and a DTC for "Fuel Pressure - Below Minimum Threshold"? A. Conduct a fuel system leak-down test B. Perform a fuel quality test C. Inspect the air filter and turbocharger operation D. Check for restrictions in the exhaust system None 11. ASE L2: Electronic Engine Controls Diagnosis A diesel engine is reporting a DTC for the exhaust gas recirculation (EGR) system performance. There are no other codes related to airflow or temperature sensors. What should be checked FIRST to diagnose this DTC? A. EGR valve operation using a bi-directional scan tool B. Intake manifold pressure C. Differential pressure across the EGR cooler D. Manifold absolute pressure (MAP) sensor None 12. ASE L2: Electronic Engine Controls Diagnosis During the cold start of a diesel engine, excessive white smoke is observed. A DTC for low compression in one cylinder is stored. What is the most likely cause of this condition? A. Faulty injector in the affected cylinder B. Worn glow plugs in the affected cylinder C. Blown head gasket near the affected cylinder D. Incorrect valve clearance for the affected cylinder None 13. ASE L2: Electronic Engine Controls Diagnosis A technician finds that a diesel engine has a rough idle and a DTC for an injector circuit fault. What should the technician inspect FIRST? A. Injector harness connector at the affected cylinder B. Fuel quality and contamination C. The camshaft position sensor signal D. Compression in all cylinders None 14. ASE L2: Electronic Engine Controls Diagnosis A diesel engine's turbocharger is not providing enough boost according to the ECM data. No DTCs are present. Which of the following is the most likely cause? A. The turbocharger wastegate is stuck open. B. There is a restriction in the air filter. C. The charge air cooler has a small leak. D. The VGT actuator is not receiving a signal. None 15. ASE L2: Electronic Engine Controls Diagnosis The ECM of a common rail diesel engine reduces power output, and a DTC for "Fuel Temperature - High" is recorded. What is the FIRST component to check? A. The fuel temperature sensor B. The fuel cooler C. The fuel heating element D. The ambient air temperature sensor None 16. ASE L2: Electronic Engine Controls Diagnosis What is the most common cause for a diesel engine's ECM to log a DTC for "EGR Flow Insufficient" when the EGR valve itself tests good? A. Carbon buildup in the EGR passages B. Faulty turbocharger C. Leaking intercooler D. EGR temperature sensor fault None 17. ASE L2: Electronic Engine Controls Diagnosis A diesel engine is producing less power and more noise than usual. The ECM has stored a DTC for "Intake Manifold Pressure - High." What should be the technician's first step in diagnosing this issue? A. Check for turbocharger overboost conditions. B. Inspect the intake manifold for cracks or leaks. C. Examine the intake air temperature sensor. D. Test the operation of the boost pressure sensor. None 18. ASE L2: Electronic Engine Controls Diagnosis A technician observes that a diesel engine's start-up is taking longer than normal. There are no DTCs present. What is a potential cause for this symptom? A. Exhaust backpressure valve is stuck closed. B. Battery terminals are corroded. C. High-pressure oil reservoir is low. D. Air intake heater relay is defective. None 19. ASE L2: Electronic Engine Controls Diagnosis When troubleshooting an active DTC for "Variable Geometry Turbocharger (VGT) Control Circuit Low," what should a technician examine FIRST? A. VGT actuator resistance and wiring B. Turbocharger shaft play and binding C. Exhaust system backpressure D. Engine oil level and quality None 20. ASE L2: Electronic Engine Controls Diagnosis When diagnosing a DTC related to "Intake Throttle Control Circuit Performance," which of the following diagnostic tests should be performed first? A. A backpressure test on the exhaust system B. A voltage drop test on the intake throttle control actuator C. Checking for proper intake manifold vacuum D. Scanning for additional DTCs that may be related to air induction None 1 out of 20 Time is Up! Time's up
